Ocean heat content increases update

There is a new paper in Nature this week on recent trends in ocean heat content from a large group of oceanographers led by John Lyman at PMEL. Their target is the uncertainty surrounding the various efforts to create a homogenised ocean heat content data set that deals appropriately with the various instrument changes and coverage biases that have plagued previous attempts.

We have discussed this issue a number of times because of its importance in diagnosing the long term radiative imbalance of the atmosphere. Basically, if there has been more energy coming in at the top than is leaving, then it has to have been going somewhere – and that somewhere is mainly the ocean. (Other reservoirs for this energy, like the land surface or melting ice, are much smaller, and can be neglected for the most part).

The main problem has been that over time the network of XBT probes and CTD casts has been replaced by the Argo float network which has a much greater coverage and more homogeneous instrumentation. However, connecting up the old and new networks, and dealing with specific biases in the XBT probes is difficult. An XBT (eXpendable Bathy-Thermograph) is a probe that is thrown off the ship and whose temperature readings as a function of time are transferred to a profile in depth from knowledge of how fast the probe falls. Unfortunately, this function is a complicated one that depends on the temperature of the water, the depth, the manufacturer of the probe etc. Various groups – working with the same basic data – have shown that there were biases in the XBT associated with incorrect calibrations and have attempted to make better corrections.

The latest paper is a consensus effort from many of the people involved in the previous work and shows how robust the recent decades warming of the ocean has been. Indeed, the ‘best estimate’ for the changes in the top 700m seems to be a greater warming than seen in the NODC data and more than even the models were suggesting:

Update (May 2012): The scaling of the model output on the original graph was incorrect, and the graph has been replaced with a corrected version. The original can still be found here.

One thing that is interesting to note is that the interannual variability – particularly in the transition period between the two observing systems (1995-2005 say) is very dependent on exactly how you do the corrections, while the longer term trend is robust. This ties in directly with comments by Kevin Trenberth in this recent paper and in an accompanying commentary to the Lyman paper that while the energy budget changes over the long term are explainable, the changes over short time frames are still very difficult to quantify.

As usual, this is unlikely to be the very last word on the subject, but this is more evidence that the planet is basically behaving as the scientists think it is. And that isn’t necessarily good news.

Good clear explanation for people who want to understand how science gets good results from instruments and cross-checks and calibrates them.

Also from that same doc: “There are no significant identified problems with the temperature sensors. Oka and Ando (2004) found no drift in temperature from 3 recovered floats after 6-9 months. They did find significant error in one of the three recovered conductivity cells (~ -0.02), from a PROVOR float, showing again the relatively larger problems with the salinity measurements from profiling floats compared to temperature measurements.”

If folks want to make a contribution to understanding of OHC measurements and in particular if they want to formulate a useful and progressive critique of Lyman et al they’re going to need to read and comprehend the entire document as well as reach a level of expertise equaling or exceeding that of Lyman and his coauthors. Failing that investment of effort, critics will need the assistance of a miracle in order to do better.

“Figure 8 shows data collected while working with hydrate mounds or with pieces of hydrate. Methane concentrations rise from a background level of ~0.1 µmols/l to a high of ~8.8 µmols/l.”http://www.nrl.navy.mil/research/nrl-review/2002/chem-biochem-research/coffin/
This indicates to me that the upper limit of CH4 concentration is about 10 µmols/l where the temperature and pressure allow formation of clathrates.

1µmol CH4 = 1.6e-5g/l = 1.6e-2 g/m^3
1.5e9 g/day/2.4e15 m^3 = ~6.3e-7 g/m^3/day = ~2.5e-6 micromolar increase per day diluted over the volume of the Gulf, However, given the 80 fold variation in concentrations observed above under much milder conditions, and the observations of clathrate formation at the wellhead, there are undoubtedly plumes of near methane saturated water(with volumes orders of magnitude less than that of the Gulf) drifting in the currents, slowly dissipating by diffusion and biogeochemical oxidation.
There are probably “blooms” of methanotrophs where the concentrations are high, and mixed populations of microbes of wildly varing composition across the methane/oxygen/temperature gradients.

According to wikipedia clathrate “… observed density is around 0.9 g/cm³. One liter of methane clathrate solid would therefore contain, on average, 168 liters of methane gas (at STP)” so the formation of clathrates near the wellhead would buoyantly transport the gas to near surface layers above the clathrate stability zone, where it would break down into bubbles and dissolve; I think that turbulence in the rising column would disperse the clathrate and bubbles widely enough that little if any would make it directly to the surface. Estimating how rapidly and how much of the Methane would diffuse into the air before being oxidized is beyond my abilities.
Methane, (plus ethane, propane, butane, etc) is also being transported dissolved in the oil that is reaching the surface – I wonder if BP is flaring off the vapor from the oil they are capturing?

The ~1.5e3 tons/day is probably not currently significant in comparison to the ~1.5e7 tons/year ocean emissions; it’s a good bet that the significant consequences will be environmental, economic, and political. The secondary effects on climate through these areas could be larger – if the Gulf seafood industry(40% of US total?) collapses, that will (in a very inequitable process) reduce fossil energy consumption and emissions in that sector. Every cloud may have a silver lining, but that is of faint comfort to those who freeze their butts off in the rain.

Hi Gavin,
Re @93. Thanks. As you know, some contrarians/deniers are capitalizing on the fact that the recently adjusted NODC 0-700m OHC data have shown a small negative slope since 2003 or so (yes, it is not a stat. sig. slope, but we know that does not matter to them). In contrast, the 0-2000 m in Lyman et al show a positive slope over the same period. So my real question is whether or not the negative slope in the NODC data circa 2003 is real or not, or if it is an artifact of measurement/processing errors. It would be nice to have someone from NODC here to explain what happened and why their curves are at odds with those of Lyman et al.

I’m inclined to go with Lyman et al’s. data, because they have gone to great lengths to correct the data and it is documented in their paper and Trenberth notes that their numbers have been independently validated, whereas NODC provide no explanation of why they adjusted their numbers downwards earlier this year and is a near-real time product without all the corrections being made.

Gavin said, “The difference is in the corrections to the XBT data, which is obviosly part of the systematic error. Lyman shows that these issues make a difference in the transition period to the Argo floats mainly.”

I’m missing something. The period most affected by Lyman et al is the present. Are XBTs used at all anymore in the calculation?

Which of course speaks to the utter bankruptcy of the “Center for Public Policy” with regard to producing any useful input to public policy. That’s why any dialog with the knuckle-dragging chimp-handlers should entirely focus on their choice of a moniker for their hapless prop, how it reflects on their seriousness of purpose, skipping the whole probability issue.

Why a troupe of Howler monkeys should be allowed in charge of a chimp is another question entirely. I feel sorry for the chimpanzee.

Off Topic: The recent Smith Megafauna paper in Nature Geoscience is being widely quoted in the media as being a possible explanation for the Younger Dryas cooling: the key paragraph in the paper appears to be:

The concentration of methane both influences and is influenced by temperature, but lead–lag and indirect relationships are not well characterized13. Ice-core records from Greenland suggest that the methane concentration change associated with a 1 °C temperature shift ranges from 10 to 30 ppbv, with a long- term mean of about 20 ppbv (ref. 13). Thus, empirically, the 185 to 245 ppbv methane drop observed at the Younger Dryas stadial is associated with a temperature shift of 9 to 12 °C. The attribution and magnitude
of the Younger Dryas temperature shift, however, remain unclear. Nevertheless, our calculations suggest that decreased methane emissions caused by the extinction of the New World megafauna could have played a role in the Younger Dryas cooling event.

The rest of the communication seems to be high quality, but this paragraph is frankly somewhat stunning: it includes all the right caveats (lead-lag relationships, attribution remains unclear) but the extrapolation of a 245 ppb CH4 drop to a 9 to 12 degree C temperature change, caveats notwithstanding, seems to me to be without justification. The 1 degree to 20 ppb relationship is almost certainly mainly in the direction temperature to methane, and not vice versa (yes, its a feedback, so it is really both ways). Not to mention that CO2 and N2O also covary with methane, so even if the entire temperature change was based on GHG changes and not orbital changes, CH4 would contribute less than half… My back of the envelope calculations suggests a forcing change of less than 0.2 W/m2 from a drop of 245 ppb – even at the upper end of the CS range this would contribute only about half a degree C to cooling…

Would this be appropriate for a short realclimate piece on scientist communication with the media (though in this case, because the statement appears in the actual text of the paper, the media isn’t really at fault at all)?

Re 111 Patrik – that could be a difficult number to derive because you need to select a baseline. What would qualify as zero heat – everything in solid form at 0 K, perhaps, but if we’re going to include the latent heat of liquifying and freezing the air, why not also include the latent heat of chemical reactions, assuming chemical equilibria are reached… etc. Then we could also discuss converting all atomic nuclei to some isotope of Fe… (?) I think it’s much easier to use anomalies. It’s a relatively simple matter to determine the change in enthalpy if some liquid water at one temperature changes to liquid water at another temperature or ice or vapor at some other temperature, etc.

If anyone tuned in after my hype, I apologize. Dude didn’t even mention climate change; it was all about dissing NOAA’s hurricane predictions. I wanted to ask if his free market- fellating org supported the Civil Rights Act, but I couldn’t get a word in edgewise. A real letdown.

I must admit, it takes an intellectually depraved simian like mentality to produce that level of rubbish, par for the course.

This simple fact that ‘Kaje’ of whom stated “I’m a mere art major with no climate expertise, but I do have a healthy skeptic streak”

is invited to speak publicly on the subject of climate as stated, “visiting a friend who’s a radio host, and I’m sitting in on the show tomorrow morning.”

to give context to a side show carnival type stunt being presented as a challenge to the scientific community is utterly ridiculous. Can anyone spot the strawman? To impugn the body of science, the scientific method and Dr. James Hansen in such manner is beyond childish, it is truly pathetic.

Furthermore, one would think one would ask a climate expert to discuss climate, or at least someone well versed in the science rather than the, as stated, ‘skeptic side’ obviously without scientific basis and of dubious bias.

Regardless of Kaje’s perspective on the matter or the fact that they did not mention climate change. It is a complete red herring/strawman to say that NOAA is not perfect, therefore science is monkey business.

This speaks volumes about the lack of scientific perspective being used by the denialst side. They have been reduced to cheap parlor tricks to present their argument.

The video is produced, according to the credit, by
‘The National Center for Public Policy Research’
501 Capitol Court, NE #200 Washington, DC 2002
Tel. (202)543-4110http://www.nationalcenter.org

Bill O’Reilly could not resist participation in the completely ludicrous media stunt which basically puts him in pinhead status when it comes to scientific method. But hey, whatever sells commercials and pleases those willing to drop down to simian status.

so, the upper ocean heat content is increasing and the polar front is getting more turbulent. what does this mean to the thickness of the so called multi-year ice? the avalanche studies tell us the layers formed in the snow are indicative of the type of avalanche expected, is there any reason not to believe that so called fractured multiyear ice won’t behave in the same style (breaks laterally)? given the salinity anomalies in the arctic ocean at http://bulletin.mercator-ocean.fr/html/welcome_en.jsp is there any reason not to believe that the saltier water penetrates the so called multi-year ice at these yearly layers or the water line of the floes? is the salinity due atlantic water or is it possible that this is indicative of the methane clathrates and the salts within them? what again was the maximum thickness of one-year ice (i recall some measurement of 230cm)? is the multi-year ice reaching these levels? is there any reason to believe multi-year ice seals the fractures in it during a winter? I think the currents from Bering sea will spread the remaining ice so the decrease in extent will slow down shortly, but that it will speed up again in about three weeks. why was august generally warmer than may, again? sorry for this inquisitive post, but some might like to find these out, and i too lack a clear picture of some of them. yours jyyh.

You are quite right that the journalism behind the Felissa Smith et al. piece was just as sloppy as the actual paper behind methane’s role concerning the Younger Dryas (as is their argument for why the “anthropocene” should be expanded backwards in time). In this case I would say it is the Nature authors to blame, although I’m not sure it is worthy of a RC piece, and I suspect the paper itself will be relatively low impact. Neither the authors themselves, nor the media reports, seem to have been able to come to grips with distinguishing between Greenland temperature anomalies vs. global temperatures. In fact the global temperature changes relatively little at the Younger Dryas due to the bipolar seesaw effect from a reduction in the AMOC. The media reports vastly overstate the sensitivity to a less than 200 ppb change in methane, and Greenland has a lot more things going on than just CH4 during the YD. I have no idea what was happening with the Nature reviewers, but at least this part of the piece should not have gotten past review.

Thank you for that work. My calculations aren’t so far off though – if typically less elegant – but we start in different places.

The estimates of leakage I find to be credible are in the range of 100 – 200 kbbl/day (of ‘stuff’). And I’ve seen (but don’t pursue) gas/crude ratios as high as 80%. We’ll skip the gas/crude ratio part of it though: leave it at your 50%.

But… at ~200 kbbl/day (rather than the ~21.6 kbbl you used – and yes, that is admittedly high; but not as high, I believe, as 21k is low) we wind up with roughly 1.5e*4* ton/day methane. Or, x365, ~5.5e6 ton/year. Still at your 50% gas/crude ratio. Yes?

Compared to the methane output from all the world’s oceans, of 1.5e7 tons/year, that does strike me as a significant number. I hope I’ve screwed up somewhere there.

If I may put my hand up again Learned Sirs! We have a series of heat sinks here. First is cold old ice in ice sheets; well below zero C. Not mobile, so the heat has to get to it by some mechanism, mainly conduction.

Then we have latent head of freezing in place on grounded and floating ice. Again heat gets into this ice by conduction.

Next we have water where the movement of the water shifts the energy around by convection and induced horizontal movements etc.

Finally we have the atmosphere where again convection and horizontal movements allow the energy to be shifted around.

My impression of heat sinks in systems where there are a series of sinks at different temperatures is that ideally they try to operate isothermally. That is, the system’s energy increases by warming the coldest bit first, and when that is up to temp then the next sink starts to warm with it, etc. So in this case the coldest ice is the prime target of the heating effort, then latent heat sinks then ocean and finally atmosphere.

Obviously in real world the rate of transport of energy from hot places to cold places (wind and current) is a factor in the rate at which each sink takes up heat. But I would have though that the atmosphere and at a slightly slower rate the ocean would be pumping as much heat as they can into ice (warm up and latent heat) until most of the ice is up to ocean temperature. Thus it seems likely that the ice is really getting hammered by the Earth’s thermal imbalance, and if that’s so then all issues related to warming ice are looking like getting worse before they get better.

> Baliunas …. throw in the towel
I hope Ike comes back to identify where that came from. I suspect he was paraphrasing; quotation marks made it appear it was a quote, but they do have other uses. I’d guess he was recalling a Tim Ball editorial very widely rebunked; you can find the quote “Sallie suddenly and politely withdrew from the fray.” Typical Ball conspiracy theory stuff.

A couple of comments-
The ocean heat content measurements(change in water temperature) are temperature measurements, similar to the atmospheric ones. They appear to behave similarly to the atmospheric measurements so they most likely are not “stationary” in the statistical sense. It is not appropriate to use a linear curve fit to the data for such short time periods.

Just looking at the graph of OHC at 700 nmeters, the most obvious feature is the change between ~1998 and ~2004(also in the NOAA graphs), which corresponds to the time period with the largest measurement uncertainty in the Lyman et.al. paper and the changeover from XBT probes to the Argo bouys. Admittedly the data is very erratic(Lyman “but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets”) (Trenberth “the messy data on upper-ocean heat content for 1993–2008 provides clear evidence for warming. But differences among various analyses and inconsistencies with other indicators merit… “). The conclusions in Lyman aren’t “robust” when the error range(up to 2.5 degC on a measurement range of ~8 deg C) is a large fraction of the measurement. It’s robust in the sense that every measurement technique shows an increase in temperature, but the wide range in results makes any measurement estimate very imprecise.

[Response: Where are you getting these units? The graph is in 10^22 Joules – and 10^22 Joules is equal to 10^22/(4180*0.7*5.1*10^14*700*1030) ~= 0.01 deg C on average over 700 meters of sea water. – gavin]

The step change from the 1970-2000 data and 2005-2010 looks really problematical. Take out the step(~7 deg C) and the so-called trend drops from 11 deg.decade(the spurious orange dotted line from 1995 to 2009) to ~1.4 deg/decade, half of the overall apparent change of 3.5 deg/decade for 1970-2009.

So what is going on? Possibly the change from XBT to Argo apparently wasn’t calibrated and the data is thoroughly messed up. At least another 30 years of Argo measurements are needed to measure what is going on.

Possibly some physical mechanism in the ocean changed- changes in rate of upper and lower ocean turnover, changes in locations of the turnover, changes in ocean currents, changes in the atmosphere affecting how much and where radiation reaches the surface or changing the heat transfer to the ocean, etc. The ocean isn’t anywhere near thoroughly mixed.

Re 127 NigelW- Nigel, the oceans/atmosphere are certainly not isothermal, and the energy definitely does not go into the coldest areas first. Just touch the asphalt on a sunny day, or dip into Lake Superior in the middle of August. Ice that melts in the sun will stick around for days in the shade. The instantaneous temperatures are highly localized and variable.

The climate and all the weather are the result of the uneven transport of heat through the system. The transport is highly localized and greatly affected by local temperatures and interactions between virtually every variable you can imagine on scales from feet to hundreds of kilometers.

re: 122. In addition, that puerile video hits the denialist’s trifecta: personal insult (on Hansen), anti-science (amazingly flaunting scientific ignorance as if gross ignorance is a good thing), and anti-government (attacking a government agency, NOAA). All that was missing from the usual mantra was an attack on EPA/regulations.

> Possibly the change from XBT to Argo apparently wasn’t calibrated
Wrong. You’ve got links above to confirm the facts. Why would you speculate without reference to easily checked facts? Just to delay?
> At least another 30 years of Argo measurements are needed
“Delay is the deadliest form of denial.”

Nigel (127), you’re pretty much correct, except where you say that systems warm the coolest bits first. Because of the whole sphere on an axis thing, we should see warm places getting warmer first – there’s more sun hitting the equator to the tropical lines that can be trapped by Ye Olde Greenhouse Effect. That warmer water is then moved to colder areas by current (most effective and efficient manner).

We pay attention to the warming of the cool parts because of the obvious, blatantly observable ice pack as it melts, but corals in some parts of the world are getting hammered as well with water too warm to be tolerated. But coral is so finicky (loads of stuff can kill coral reefs), that it’s much safer to look at ice.

” Thus it seems likely that the ice is really getting hammered by the Earth’s thermal imbalance, and if that’s so then all issues related to warming ice are looking like getting worse before they get better.”

Dead on the money.

Thirty years ago territorial limits within the Artic Circle were limited to academics and largely philosophical debates. Today we find Canada reiterating it’s claim that Longitude extends perpendictular to their coast (and doesn’t curve to the pole) and the Russians intensely mapping and claiming that the continental shelf extends from their coast to the North Pole (one way to determine limits of territory). Both are pre-emptive measures for when the Polar ice cap is no more and can be exploited for minerals and navigation.

Heat the water around a cold landed place and it’ll warm up, too. The main watchword is Greenland, as it lays pretty close to the great Gulf Stream conveyor and holds a helluvalot of water tied up as ice. Melting floating ice doesn’t raise sea levels – it’s already accounted for – but melting and adding water from land does.

And huge thanks to all for fixing my maths. I was driving back from the store and did a face palm thinking about what I did wrong, only to be relieved that someone had caught my errors.

So what is going on? Possibly the change from XBT to Argo apparently wasn’t calibrated and the data is thoroughly messed up. At least another 30 years of Argo measurements are needed to measure what is going on.

Besides Hank’s comment noting that you are indulging yourself in pointless speculation, positing a question that remains unanswered purely as your own personal artifact in your own head, let’s establish one important point of agreement or disagreement.

Do you believe the difference in OHC reflected between the x-y origin of the graph and the end of the data presented is an error?

It was never intended for me to offer “expertise” on this guy in lieu of an actual expert. I took (or tried to take, but I couldn’t bring the subject up) that up by myself after I found out details about the guest. My original purpose there was to banter with the hosts for the day, and get Jewel’s autograph (her being the other guest).

I’ve since learned that the hosts themselves were planning to mock the guy, but it didn’t pan out that way. Also, it seems he was mainly invited to rip on NOAA, because the hosts crossed swords with them in the past. (NOAA got mad at them because they joked about putting bourbon in emergency kits.)

So the guy plugged his monkey, we never got around to making fun of his ideology, and Jewel ended up running late and I just gave her bunny ears in a picture instead. Which didn’t show up in the picture. Suckage.

While there is something called the Arctic amplification effect, it does not necessarily mean the Arctic ocean is warming faster. More related to the general parameter differences of the northern hemisphere.

The oceans overturn heat content through oceanic currents. I don’t know much about Arctic ocean currents, but I would venture they actually do mix with other oceans. Extent of interactions and heat exchange?

So the question does not have enough specificity or understanding in its base to know what it is asking.

No worries, I was trying merely to point out that if they are choosing art majors to discuss NOAA and the pathetic carnival media stunt id est hansimian, it shows how out of touch the debate really is from that end of the farm.

Nigel,
I think storage of heat via ice temperature change is generally ignored. For an ice sheep, responce of deeply buried ice temperature to surface temperatures would be expected to be very slow. Thermal conduction is too slow to penetrate more than a few meters in relevant timescales. Heat (or its lack) does get advected downwards in the accumulation zone of an ice sheep, as ice is gradually buried, and extension in the horizontal direction. In equilibrium the vertical ice velocity at the surface would be the same as the net accumulation rate (generally a few tens of centimenters per year), so AGW effects will not have had time to penetrate beyond maybe 10 or twenty meters depth. That leaves only meltwater penetration as a potential way to inject surface heat deep into the ice sheet. I think deep meltwater penetration only ocurrs where there is enough summer melting to form surface lakes, which can drain deeply (probably to the base). But only the edge areas of the greenland ice sheet are warm enough for this to ocurr. I think the total surface area involved is not so great as to have much impact of the planets total storage of heat. I don’t think it is well known how much meltwater refreezes in the glacier, versus how much escapes to the oceans. The antarctic is too cold for this mechanism to matter there. So again the areas/volumes involved are orders of magnitude smaller than of the oceans, so I don’t think the error of omission is significant.

As only the first few millimetres of the oceans at most absorb long wave radiation emitted by GHGs and it is unlikely that this layer stops evaporation of heat from the oceans how can GHGs influence oceanic heat storage directly? Isn’t the only mechanism for GHG heating through heating the atmosphere above the oceans?

At what point does winter sea ice not form is the essence of the question. This would require seemingly require the Arctic ocean to be warmer so that the pole would be kept ice free. It has happened at some point on the past where the continents poition and the ocean currents were similar to today. Antartica started to develop its glaciers 34 million years ago and the Arctic around 5? Any evidence of either poles being ice free or have seen serious ice degredation during this time. For example has the Arctic ever been sea ice free during the winter?